1. Technical Field
The present disclosure relates to a vehicle seat airbag system and a vehicle seat, and particularly to a vehicle seat airbag system and a vehicle seat equipped with an airbag within a seat back of the seat.
2. Related Art
In a vehicle seat such as an automobile seat, an airbag system is known that protects a seated person against an impact at the time of a collision by inflation and development of an airbag which is disposed in a seat back.
For example, the vehicle seat disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 10-273000 includes a seat pad on the front surface of an elastic installation supporting member which is installed inward of a seat back frame, and an airbag in a contracted state is disposed in a space between the elastic installation supporting member and a supporting plate which is disposed rearwardly of the elastic installation supporting member and has a robust structure.
With this vehicle seat, an operation of an inflator corresponding to detection of an impact greater than or equal to a predetermined value causes the airbag to inflate between the elastic installation supporting member and the supporting plate so that rearward movement of a seated person at the time of a collision is elastically supported and regulated from the rear, and the impact energy is absorbed by pressure reduction and contraction of the airbag.
In Japanese Unexamined Patent Application Publication (JP-A) No. 2010-52621, a first airbag, which is designed to inflate and develop toward a seated person on the rear seat, is installed in the lower portion of the rear surface of the seat back of the front seat, and a second airbag in a flat state is disposed on the front surface of an elastic installation supporting member which is installed inside a seat back frame within the seat back of the front seat.
Consequently, an operation of an inflator corresponding to detection of an impact greater than or equal to a predetermined value causes the first airbag to inflate and develop toward a seated person on the rear seat, thus even when the seated person on the rear seat is moved forward due to an impact at the time of a collision, the seated person is prevented from strongly hitting the rear surface of the seat back of the front seat. Furthermore, rearward movement of the upper body of a seated person on the front seat at the time of a collision is elastically supported, regulated from the rear and protected by the inflation and development of the second airbag. The inflation timing for the first and second airbags is controlled, and an appropriate protection for a seated person is achieved.
As described above, the vehicle seat disclosed in JP-A No. 10-273000 achieves the protection of a seated person on the vehicle seat by the presence of the air bag and the supporting plate which is disposed outward rearwardly of the air bag and has a robust structure. That is, the impact of rearward movement of a seated person is reduced by the airbag, and an impact applied from the rear of the seat back is received by the supporting plate and is absorbed by the airbag.
Therefore, when a rear seat is present and a seated person is on the rear seat, a collision of the seated person with the front seat from the rear of the seat back causes a large impact when the seated person collides with the supporting plate. Therefore, an impact from the rear cannot be received softly, which may cause not only a damage to the knees of the seated person on the rear seat, but also a significant impact to the person on the front seat.
On the other hand, according to the airbag device in JP-A No. 2010-52621, protection of the seated person on the front seat and reduction in damage may be expected by the second airbag that inflates and develops within the seat back of the front seat. Also, protection of the seated person on the rear seat is achieved by the first airbag that inflates and develops toward the seated person on the rear seat. However, not only the airbag device needs to be provided within the seat back, but also the first airbag, which inflates and develops toward the seated person on the rear seat, needs to be separately provided in the lower portion of the seat bag of the front seat. Thus, the structure of the seat bag becomes more complicated and control load for each airbag increases.
In addition, the first airbag significantly expands diagonally upward from the lower portion of the rear surface of the seat back of the front seat toward the seated person on the rear seat, and thus the inflation and development pattern becomes unstable, which does not provide sufficient stability for accurately, reliably receiving a collision of the seated person on the rear seat with the seat back of the front seat, and for absorbing the impact.
As described above, in each structure of the above-described conventional arts, there is a possibility of further improvement on direct protection of the seated person on the front seat by the airbag and protection against an impact to the seat back from the rear by adopting a simple structure.
In a vehicle such as an automobile, such a collision of the knees of the seated person on the rear seat with the seat back of the front seat may occur not only at a front-end collision, but also in a situation where the seated person on the rear seat is pushed forward due to deformation of the rear part of the vehicle at the time of a rear-end collision and the knees of the seated person strongly collides with the rear surface of the seat back of the front seat.